1. Field of the Invention
The present invention relates to a DNA aptamer specifically binding to EN2 (Engrailed-2), a biosensor for diagnosing prostate cancer having the same and a method of diagnosing prostate cancer.
2. Discussion of Related Art
Prostate cancer is the most common cancer in men, and 30% of men aged over 50 years are estimated to be diagnosed with prostate cancer. According to a plurality of cases of clinical evidence, prostate cancer is considered to have bone metastasis, and it is known that an androgen-dependent state inevitably progresses to an androgen-insensitive state which results in an increase in the death rate of patients. Furthermore, since prostate cancer recurred in about 25% of men who had undergone prostate cancer treatments, additional treatments are required. Currently, prostate cancer is the second cause of cancer death in men in the USA, and early diagnosis and treatments therefor are necessary.
Direct methods among currently used prostate cancer diagnostic methods include a prostate direct illumination method of and a biopsy. When diagnosis is performed using the direct illumination method or the biopsy, it is difficult to diagnose the onset of prostate cancer at an early stage. Therefore, the development of a method that can be used to perform early in vitro diagnosis is urgent.
Indirect methods include a diagnostic method that can be used to perform in vitro examination using a prostate-specific antigen (PSA) test. However, PSAs used for diagnosis are generated not only in malignant prostate epithelial tissues but also in the normal and benign cells, which causes a high false positive rate in prostate cancer detection. Also, when a serum PSA level is very high, the PSA test can be used as an effective standard diagnostic method of prostate cancer. However, when the PSA serum level is low, for example, 2-10 ng/mL, it is difficult to perform reliable prostate cancer diagnosis. As described above, when a PSA concentration is low, the serum PSA can be produced from non-tumor diseases such as benign prostatic hyperplasia (BPH), prostatitis or other physical injuries. Therefore, PSA analysis for prostate cancer diagnosis has a detection specificity problem.
Therefore, diagnosis of prostate cancer using a new biomarker has become a main object, and research thereon has been conducted (Korean Patent No. 10-2009-0111307), but there is much to be desired.